I have a single turbo FD (HKS T51R KAI), which Geff at REWorx mapped to 421bhp at 0.85bar boost. It hits 83-84% injector duty cycle at full boost, which from reading I gather is seen as a safe limit by many.
Clearly, to achieve this, the fuel pressure has been raised by an FPR (I don\'t know what to) and from the electrical whine from the back of the car, an uprated fuel pump (I can\'t imagine the stock item is capable of enough fuel from what I have read).
I\'m not bothered about making any more power, but I do want to know that the setup is safe, both in terms of reliability and literally - I don\'t want petrol spraying around at a high pressure!
Those in the know - does the current setup sound acceptable, or are there solid safety (or other) reasons for upgrading to a secondary rail/1680cc injectors?
I do believe there is a jubilee clip used on the fuel line as part of the FPR insallation, which strikes me as dubious - should I replace it with another type of connector?
well i ran 400bhp non seq on standard setup and it used to max at 92% inj duty. i run an fpr and bosch 044 in the tank ive never had an issue in last 4 years and mine was setup at re worx aswell. im now running 850\'s all round as last year on a track day in middle of the summer i hit 100% inj duty now my duty hits under 80% most of the time and only went upto around 82% at castle coombe recently.
i would say from the sound of it yours is fine.
before you decide its not safe, stick a fuel pressure gauge on the system and see what the fuel pressure base rate is without the engine running. Mazda only use sprung type clips for all their fuel system so they cant be that bad!
The base pressure from Mazda is 43 psi and then rises to what ever boost you run on top. Anything up to about 55psi base is considered fairly \'safe\'
Ah, cheers guys. So I need to get a fuel pressure gauge and check what\'s happening - but presumably the FPR is rising rate, so how will I know the max it\'s reaching? Or will that simply be base + boost as you say?
In which case, at 0.85bar, I\'m adding 12.3psi. Will I need the ignition on to have the pump primed when testing the pressure?
When you say up to 55psi is considered "safe", why is greater pressure unsafe? Is it because the fittings give way, the injectors leak etc.?
when you turn the ignition on the pump should prime for about 10 seconds or so if the stock wiring is used. This is when you need to check the pressure gauge, you must check it when the pump is pumping as the pressure drops quickly after the pump stops. Or you can start the engine and pull the vacuum line of the top of the regulator, it will give you the same reading. It will be lower at idle if the line is still attached.
The above will give you the base rate, with the vacuum line connected, the boost will go down slightly at idle due to the vacuum but will rise 1-1 for each psi of boost, the fuel pressure will rise 1 psi, So if you run 13psi and stock fuel pressure 43psi, then at full boost the fuel pressure goes up to 56 psi. It maybe worth sticking a piccy of you fpr as there are some that are 1-3 or even 1-7 which shouldnt really be used but some do.
just like anything pressurised, the higher the pressure the more likelihood of it leaking.
to be honest if your car was setup and mapped at reworx they will of checked fueling and pressure and made sure everything was sorted. if thats what you had done i really wouldnt be worrying about it.
my car was originaly mapped there i get my map checked every year there to make sure everything is fine and if there is the slightest problem with fuel,fuel pressure,voltage drop or anything they tell you straight away.
Cyman, I appreciate what you\'re saying, I did have Geff give the car a good once-over as well as the mapping, so I would expect it to be safe, but I don\'t know a whole lot about this subject and I thought I would check it out.
Ant, thanks for the tips. Attached are pics of the FPR (I think! Looks a bit like an HKS one from pics I have found) and the braided hose with the jubilee clip that I\'m seeking reassurance on! ;)
looks fine to me, as Tony said, Mazda didnt even use screw on jubilee clips just the sprung type to hold fuel hoses on
That FPR looks exactly like mine - so it is an HKS unit.
It\'s standard rising rate - 1:1 so for each psi of boost, fuel pressure goes up 1psi too. I see you\'ve used AN fittings - I\'ve run 40psi+18 psi boost on top with no issues - I believe the regulator has a quoted range of 28~71 psi, so provided your static (no vacuum) pressure and boost together don\'t exceed 71 psi you\'re fine on the FPR.
I\'d not want to rely on standard fuel hose clips though - AN fittings are a much safer and better bet, but having said that the fuel system in a stock car should be rated to 80psi at least.
I\'d have thought to run 420ish bhp you\'d need VERY high base pressure on stock injectors. I\'d suspect that you have the pressure upped a bit and are maybe running 850\'s all round?
Quote from: SiH;765906I\'d have thought to run 420ish bhp you\'d need VERY high base pressure on stock injectors. I\'d suspect that you have the pressure upped a bit and are maybe running 850\'s all round?
Well, depending what you read, 400rwhp is about the limit of the stock injectors, according to RX7club.com posts and some other US websites I\'ve seen. So 421bhp flywheel is within the range.
Can you tell by looking at said injectors in situ, or would you have to take them out to see if they\'re 850s? That said, I imagine it ain\'t easy getting to them just for a nosey anyway...
Prof, thanks for the FPR info, that\'s useful :)
I guess it all depends on what pressure the pump is putting out to start with then - time to locate a fuel pressure gauge!
Quote from: lockwood77;765913I guess it all depends on what pressure the pump is putting out to start with then - time to locate a fuel pressure gauge!
You can get an inline AN6 to AN6 with 1/8 BSP gauge take off - that\'s what I use on mine - that way you can see the fuel pressure when setting up / dyno etc.
That\'s what I use on my setup:
http://www.mazdarotaryclub.com/forums/attachment.php?attachmentid=46485&d=1267998502
Thanks, hopefully I can fit one in, then I\'ll know for sure! :)
Quote from: lockwood77;765913Well, depending what you read, 400rwhp is about the limit of the stock injectors, according to RX7club.com posts and some other US websites I\'ve seen. So 421bhp flywheel is within the range.
Yarr, but 400USATWBHP ~ less UKATFBHP
i cant tell from the photo but if the braided hose is on the fuel return then its not so important as its low(er) pressure. The return is the one that comes out of the bottom of the FPR.
Also the fuel pressure from the pump is irrelevant, its all down to the FPR. ie, an 044 can push up to 10bar pressure.
OK, gotcha. Looks like a gauge and suitable fittings won\'t be too expensive, so will try and get that done. Poking around further I can see that there are jubilee clips on both send and return braided hoses, will take a view on them once I know what pressure it\'s running at.